ERL2019 - Table of Session: WEPNEC (Poster Session)

Paper	Title	Page
WEPNEC01	Status and Future Perspective of the TRIUMF E-Linac	70
	S.D. Rädel, M. Alcorta, F. Ames, E. Chapman, K. Fong, B. Humphries, O.K. Kester, D. Kishi, S.R. Koscielniak, R.E. Laxdal, Y. Ma, T. Planche, M. Rowe, V.A. Verzilov TRIUMF, Vancouver, Canada
	The currently installed configuration of TRIUMF’s superconducting electron linac (e-linac) can produce an electron beam up to 30MeV and 10mA. Low beam power commissioning of the segment spanning the electron gun to high energy dump took place in summer 2018 with an attained beam energy of 25MeV. As the driver of the ARIEL project, the e-linac will deliver electrons to a photo-converter target station for the production of neutron-rich rare isotope beams (RIB) via photo fission. The e-linac will have sufficient beam power to support the demands of other user community rare isotope beams. This driver accelerator could server as a production machine for high field THz radiation and as irradiation center. A recirculation of the beam would be beneficial for RIB production at higher beam energy and would allow for high bunch compression to generate THz radiation. Such a system would also allow for the investigation of a high beam intensity energy recovery linac. To this end, TRIUMF is investigating the design of such a recirculation and the beam dynamics as a first step.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC01
About •	paper received ※ 01 October 2019 paper accepted ※ 01 November 2019 issue date ※ 24 June 2020
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WEPNEC02	Investigation and Mitigation of the Mie-Scattering on the Surface of the First Objective Lens for Coronagraph-Based Halo Monitor
	J.G. Hwang, J. Kuszynski HZB, Berlin, Germany
	Funding: This work was supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association. Since, due to the heat capacity of the cryogenics, additional heat load on a cryogenic system as a result of uncontrolled beam losses is only allowed to be below 50 W which corresponds to 10^-5 respected to the full power of BERLinPro, the development of diagnostics which can measure the intensity in the order of 10^-5 is crucial. In our previous beam test of the coronagraph-based halo monitor with various operation modes of the BESSY II storage ring, the limitation of the measurement of the halo distribution was to be 10^-4 respected to the core intensity due to the noise produced by scattered light from digs and scratches of the first objective lens. In order to mitigate the noise level produced from the surface of the objective lens to reach 10^-5 to 10^-6, the Mie-scattering effect was investigated, and furthermore, a high-quality surface lens was purchased.
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WEPNEC03	Thermal Load Studies on the Photocathode Insert with Exchangeable Plug for the BERLinPro SRF-Photoinjector
	N. Al-Saokal, M. Bürger, M. Dirsat, A. Frahm, A. Jankowiak, T. Kamps, G. Klemz, J. Kühn, S. Mistry, A. Neumann, H. Plötz HZB, Berlin, Germany
	For the operation of an SRF photoinjector a well-functioning and efficient cooling system of the photocathode is necessary. A test experiment was set up of the photocathode cooling system based on the original components, which we call thermal contact experiment (TCX). We present the results of our thermal load studies on the photocathode insert with exchangeable photocathode plug. The goal was to test all components before they are installed in the cold string of the BERLinPro SRF-Photoinjector to ensure the operation of very sensitive semiconductor photocathodes. The tests include the investigation of the cooling performance, the thermal load management and the mechanical stability of the photocathode insert.
	Poster WEPNEC03 [1.703 MB]
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WEPNEC04	HOM Damping for High Current SRF Cavity
	W. Xu BNL, Upton, New York, USA
	Funding: * Work supported by LDRD program of Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE. High power HOM damper is a challenge for high current SRF accelerator. In the past few years, we developed two types of high power HOM damper: a novel rigid waveguide high power HOM damping scheme and a room temperature SiC beampipe absorbing scheme. This presentation will present the design and test results of these two HOM damping schemes.
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WEPNEC06	Radiation Protection Instrumentation of BERLinPro
	L. Pichl, Y. Bergmann, A. Bundels, K. Ottpresenter HZB, Berlin, Germany
	Funding: Work supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association The Energy Recovery Linac project BERLinPro is a test facility to study the beam parameter range necessary for an ERL as synchrotron light source [1]. It is currently under construction and is designed to operate with the maximum beam parameters of 50 MeV and 100 mA cw current. Even if the electron losses within the recirculator are limited to 0.6 % due to the available rf power, (at higher losses an immediate beam break-up occurs because of the ERL principle) the beam loss power can be by orders of magnitude higher than in electron storage rings used for synchrotron radiation. The Fluka [2,3] calculations of the resulting activations of machine components and air activations have been discussed in earlier papers [4,5]. In this work we present the components of the ambient dosimetry, the measurement system of air activations and their inclusion in the personal safety system. Additionally we present recent calculations of the activation of cooling water and the method of storing and measuring it in case of a leakage. 1 M Abo-Bakr et al SRF2009 Berlin 2 G Battistoni et al AIP Conf. Proc. 896 2007 3 A Fasso et al CERN-2005-10 2005 4 M Helmecke et al RADSYNCH2013 BNL 5 K Ott et al RADSYNCH2015 DESY
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WEPNEC07	Comparison of Two Pareto Optimization Tools Using OPAL and ASTRA for a Dedicated BERLinPro Injector Optimization.
	J. Völker HZB, Berlin, Germany A. Adelmann PSI, Villigen PSI, Switzerland
	BERLinPro is an Energy Recovery Linac (ERL) Project, currently being set up at the HZB. The accelerator consists of an injector part (SRF photo injector and booster section) and the ERL part (LINAC and recirculator section). Until realization of the final ERL setup further beam applications are under development using only the injector part of BERLinPro, like ultrafast electron diffraction (UED) or tomography experiments. For those cases a dedicated beam optic for the complete injector is required that differ from the standard ERL optics. Especially for UED experiments, an extreme short electron bunch and a tiny transverse emittance are needed. For the optimization of the injector two multi-parameter Pareto optimization tools were used. On the one hand, ASTRA with an external MATLAB optimizer, on the other hand, OPAL** with its new internal optimization tool. In this paper we will present both generic methods and compare their results.
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WEPNEC08	Dispersion Matching With Space Charge in MESA	74
	A. Khan, O. Boine-Frankenheim TEMF, TU Darmstadt, Darmstadt, Germany K. Aulenbacher IKP, Mainz, Germany
	Funding: Supported by the DFG through GRK 2128. For intense electron bunches traversing through bends, as for example the recirculation arcs of an Energy-Recovery Linac (ERL), dispersion matching with space charge of an arc into the subsequent radio-frequency (RF) structure is essential to maintain the beam quality. We show that beam envelopes and dispersion along the bends and recirculation arcs of an ERL, including space charge forces, can be matched to adjust the beam to the parameters of the subsequent section. The present study is focused on a small-scale, double-sided recirculating linac Mainz Energy-recovering Superconducting Accelerator (MESA). MESA is an under construction two pass ERL at the Johannes Gutenberg-Universit\"at Mainz, which should deliver a continuous wave (CW) beam at 10⁵ MeV for physics experiments with a pseudo-internal target. In this work, a coupled transverse-longitudinal beam matrix approach for matching with space charge in MESA is employed.
	Poster WEPNEC08 [1.190 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC08
About •	paper received ※ 12 September 2019 paper accepted ※ 01 November 2019 issue date ※ 24 June 2020
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WEPNEC09	Thz User Operation With 200 pC CW Beam Generated by the ELBE SRF Gun II
	A. Arnold, S. Ma, P. Murcek, J. Schaber, J. Teichert, R. Xiang, P.Z. Zwartek HZDR, Dresden, Germany
	Funding: The work was partly supported by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1 and Deutsche Forschungsgemeinschaft (DFG) project (XI 10⁶/2-1) As a new electron source with higher brilliance, the second superconducting RF photoinjector (SRF Gun II) has been built at the ELBE radiation center for high power radiation sources. One of the main goals of SRF gun II is to achieve a higher bunch charge (>200 pC) and lower emittance (3 mm mrad) than the present ELBE thermionic DC gun. SRF Gun II features a 3.5-cell niobium cavity as well as a superconducting solenoid in the same cryomodule. With Mg photocathodes the gun is able to provide medium current beam with bunch charge of more than 200 pC and sub-ps bunch length at 100 kHz repetition rate. With this contribution we present convincing results from long-term user operation of SRF gun II in combination with the bunching concept of the ELBE accelerator in order to produce THz radiation with much higher stability and power than available using the existing thermionic gun.
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WEPNEC10	Investigation on the Ion Clearing of Multi-Purpose Electrodes of BERLinPro	80
	G. Pöplau COMPAEC e.G., Rostock, Germany A. Meseck KPH, Mainz, Germany A. Meseck HZB, Berlin, Germany
	High-brightness electron beams provided by modern accelerators require several measures to preserve their high quality and to avoid instabilities. The mitigation of the impact of residual ions is one of these measures. It is particularly important if high bunch charges in combination with high repetition rates are aimed for. This is because ions can be trapped in the strong negative electrical potential of the electron beam causing emittance blow-up, increased beam halo and longitudinal and transverse instabilities. One ion-clearing strategy is the installation of clearing electrodes. Of particular interest in this context is the performance of multi-purpose electrodes, which are designed such that they allow for a simultaneous ion-clearing and beam-position monitoring. Such electrodes will be installed in the BERLinPro facility. In this contribution, we present numerical studies of the performance of multi-purpose clearing-electrodes planned for BERLinPro, i.e. we investigate the behavior of ions generated by electron bunches while passing through the field of the electrodes. Hereby, several ion species and configurations of electrodes are considered.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC10
About •	paper received ※ 11 October 2019 paper accepted ※ 06 November 2019 issue date ※ 24 June 2020
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WEPNEC11	X-Ray ICS Source Based on Modified Push-Pull ERLs	84
	I. Drebot, A. Bacci, S. Cialdi, L. Faillace, D. Giannotti, M. Rossetti Conti, A.R. Rossi, L. Serafini, M. Statera, V. Torri INFN-Milano, Milano, Italy A. Bosotti, F. Broggi, D. Giove, P. Michelato, L. Monaco, R. Paparella, D. Sertore INFN/LASA, Segrate (MI), Italy P. Cardarelli, M. Gambaccini, G. Paternò, A. Taibi INFN-Ferrara, Ferrara, Italy A. Esposito, A. Gallo, C. Vaccarezza INFN/LNF, Frascati, Italy G. Galzerano POLIMI, Milano, Italy M. Gambaccini UNIFE, Ferrara, Italy G. Mettivier, P. Russo UniNa, Napoli, Italy V. Petrillo, F. Prelz Universita’ degli Studi di Milano & INFN, Milano, Italy E. Puppin Politecnico/Milano, Milano, Italy A. Sarno INFN-Napoli, Napoli, Italy
	We present the conceptual designs of BriXS and BriXSino (a minimal test-bench demonstrator of proof of principle) for a compact X-ray Source based on innovative push-pull ERLs. BriXS, the first stage of the Marix project, is a Compton X-ray source based on superconducting cavity technology with energy recirculation and on a laser system in Fabry-Pérot cavity at a repetition rate of 100 MHz, producing 20-180 keV radiation for medical applications. The energy recovery scheme based on a modified folded push-pull CW-SC twin Linac ensemble allows to sustain MW-class beam power with almost just one hundred kW active power dissipation/consumption.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC11
About •	paper received ※ 20 September 2019 paper accepted ※ 06 November 2019 issue date ※ 24 June 2020
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WEPNEC12	Beam Optics of Bunch Compression at Compact ERL
	M. Shimada, Y. Honda, R. Kato, T. Miyajima, N. Nakamura, T. Obina KEK, Ibaraki, Japan
	Short electron bunch is essential for THz coherent transition radiation or FEL oscillation. Therefore, the bunch compression is studied at the compact ERL in KEK site. We demonstrated it and experimentally evaluated the bunch length and the transverse emittance. The results of the optics and beam commissioning will be presented.
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WEPNEC13	Preliminary Investigations and Pre-Research Scheme of High Average Current Electron Injectors at IMP	90
	Q.T. Zhao, J.C. Yang, Z.M. Zhang, H.W. Zhao IMP/CAS, Lanzhou, People’s Republic of China
	High average current electron injectors are desired by high average beam power SRF linacs. With respect to the different linac application, different beam qualities are required. Two kinds of electron gun are planned for future projects at IMP, one is thermionic electron gun dedicated for high average current, and another one is photocathode gun which is for high average current and high beam quality or even with high polarization. Current status and development of the high average current electron source are investigated and summarized. The thermionic gun studies are planned and the feasible types of gun for the future Electron ion collider of China (EicC) project are also proposed. The pre-research scheme of these two kinds of electron guns are schemed, which will be the start of high average current and high-quality electron source development at Institute of modern physics (IMP), Chinese academy of sciences (CAS).
	Poster WEPNEC13 [0.827 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC13
About •	paper received ※ 22 September 2019 paper accepted ※ 01 November 2019 issue date ※ 24 June 2020
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WEPNEC14	Electromagnetic Design of a Superconducting dual axis Spoke Cavity*	94
	Ya.V. Shashkov, N.Yu. Samarokov MEPhI, Moscow, Russia I.V. Konoplev JAI, Oxford, United Kingdom
	Funding: The reported study was funded by RFBR according to the research project 18-302-00990 Dual axis superconducting spoke cavity for Energy Recovery Linac application is proposed. Conceptual design of the cavity is shown and preliminary optimiza-tions of the proposed structure have been carried out to minimize the ratio of the peak magnetic and electric fields to the accelerating voltage. The new design and future work are discussed
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC14
About •	paper received ※ 01 October 2019 paper accepted ※ 06 November 2019 issue date ※ 24 June 2020
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WEPNEC16	Electron Outcoupling System of Novosibirsk Free Electron Laser Facility - Beam Dynamics Calculation and the First Experiments	98
	Ya.V. Getmanov, A.S. Matveev, O.A. Shevchenko, N.A. Vinokurov BINP SB RAS, Novosibirsk, Russia Ya.V. Getmanov, A.S. Matveev, N.A. Vinokurov NSU, Novosibirsk, Russia
	The radiation power of the FEL with optical cavity can be limited by the overheating of reflecting mirrors. In the electron outcoupling scheme electron beam radiates the main power at a slight angle to the optical axis. For this, it is necessary to divide undulator by a dipole magnet at least in two parts - the first for the electron beam bunching in the field of the main optical mode, and the second for the power radiation by deflected beam. Electron outcoupling system is installed on the third FEL based on the multiturn energy recovery linac of the Novosibirsk Free Electron Laser facility (NovoFEL). It consists of three undulators, dipole correctors and two quadrupole lenses assembled between them. There are two different configurations of the system since the electrons can be deflected in either the second or the third undulator. The electron beam dynamics calculations and the results of the first experiments are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC16
About •	paper received ※ 01 October 2019 paper accepted ※ 06 November 2019 issue date ※ 24 June 2020
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WEPNEC17	Developments in Photocathode R&D at STFC Daresbury Laboratory: New Transverse Energy Spread Measurements and the Development of a Multi-Alkali Photocathode Preparation Facility	103
	L.B. Jones, B.L. Militsyn, T.C.Q. Noakes STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom L.B. Jones, D.P. Juarez-Lopez, B.L. Militsyn, T.C.Q. Noakes, L.A.J. Soomary, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom D.P. Juarez-Lopez, L.A.J. Soomary, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	Photocathode R&D activity within ASTeC is focussed on further development of the tools required for the preparation and characterisation of high performance photocathodes for X-FELs. Our Transverse Energy Spread Spectrometer (TESS)* experimental facility can be used with III-V semiconductor, multi-alkali and metal photocathodes to measure transverse and longitudinal energy distributions of the emitted electrons. Recently TESS has been upgraded to increase the instrument sensitivity for operation with low QE materials under UV illumination. Our R&D facilities also include in-vacuum quantum efficiency measurement, XPS, STM, plus ex-vacuum optical and STM microscopy for surface metrology. Intrinsic photocathode emittance is affected by many factors including illumination wavelength and surface roughness. We present energy distribution measurements for electrons emitted from copper, niobium and zirconium photocathode samples with measured levels of surface roughness under illumination by wavelengths between 256 and 291 nm. We also present an update on progress to establish a multi-alkali photocathode preparation facility to support the CLARA** linear accelerator. * Proc. FEL’13, TUPPS033, 290-293 ** CLARA Conceptual Design Report J. Inst. 9 T05001
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC17
About •	paper received ※ 04 October 2019 paper accepted ※ 01 November 2019 issue date ※ 24 June 2020
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WEPNEC18	Analytic Longitudinal Phase Space Solutions for Multipass Energy Recovery Linacs
	P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom I.R. Bailey, P.H. Williams Cockcroft Institute, Warrington, Cheshire, United Kingdom I.R. Bailey Lancaster University, Lancaster, United Kingdom T.K. Charles The University of Melbourne, Melbourne, Victoria, Australia T.K. Charles CERN, Geneva, Switzerland G. Perez-Seguranapresenter Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
	The longitudinal solution space of an energy recovery linac is an under-constrained system. For applications where we wish to compress the bunches for delivery to, for example, a free-electron laser or an interaction point, and simultaneously ensure full recovery it is useful to be able to rapidly ascertain and assess the possible solutions. Moreover, when we consider multi-pass ERLS, we quickly conclude that a trial-and-error approach to deriving such solutions (through for example one-dimensional particle tracking) is impractical. Here we extend an analytic recurrence method of deriving phase space solutions in multistage compression schemes, due to Zagorodnov & Dohlus, to multi-pass energy recovery linac systems. We use this method to categorise classes of solutions, and explore the implications of the energy recovery condition.
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WEPNEC19	Optimisation of the PERLE Injector	107
	B. Hounsell, M. Klein, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom B. Hounsell, B.L. Militsyn, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom B. Hounsell, W. Kaabi Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France B.L. Militsyn STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The injector for PERLE, a proposed electron Energy Recovery Linac (ERL) test facility for the LHeC and FCC-eh projects, is intended to deliver 500 pC bunches at a repetition rate of 40.1 MHz for a total beam current of 20 mA. These bunches must have a bunch length of 3 mm rms and an energy of 7 MeV at the entrance to the first linac pass while simultaneously achieving a transverse emittance of less than 6 mm mrad. The injector is based around a DC photocathode electron gun, followed by a focusing and normal conducting bunching section, a booster with 5 independently controllable SRF cavities and a merger into the main ERL. A design for this injector from the photocathode to the exit of the booster is presented. This design was simulated using ASTRA for the beam dynamics simulations and optimized using the many objective optimization algorithm NSGAIII. The use of NSGAIII allows more than three beam parameters to be optimised simultaneously and the trade-offs between them to be explored.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC19
About •	paper received ※ 01 October 2019 paper accepted ※ 11 November 2019 issue date ※ 24 June 2020
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WEPNEC20	A Hard X-ray Compact Compton Source at CBETA
	J. Crone, H.L. Owen UMAN, Manchester, United Kingdom K.E. Deitrick, C. Franck, K.W. Smolenski Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA B.D. Muratori Cockcroft Institute, Warrington, Cheshire, United Kingdom B.D. Muratori STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Compton backscattering at energy recovery linacs (ERLs) promise high flux, high energy x-ray sources in the future, made possible by high quality, high repetition rate electron beams produced by ERLs. CBETA, the Cornell-Brookhaven accelerator currently being commissioned at Cornell, is an SRF multi-turn ERL using Non-Scaling Fixed Field Alternating Gradient (NS-FFA) arcs. CBETA has high quality design parameters with an anticipated top energy of 150 MeV on the fourth pass. The expected parameters of a Compton source at CBETA include a top x-ray energy of over 400 keV with a flux on the order of 10¹² ph/s. One particular application requiring a high energy, high flux source is spectroscopy in high energy atomic physics. In this paper, we present anticipated parameters and potential applications in science and engineering for this source.
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WEPNEC21	Decoupling Cathode and Lattice Emittance Contributions from a 100 pC, 100 MeV Electron Injector System	112
	N.P. Norvell SLAC, Menlo Park, California, USA M.B. Andorf, I.V. Bazarov, C.M. Gulliford, J.M. Maxson Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	We present simulation results to decouple the emittance contributions that are intrinsic from the injector lattice versus emittance contributions due to the quality of the cathode out of a 100 MeV electron injector system. Using ASTRA driven by the NSGA-II genetic algorithm, we optimized the LCLS-II injector system with a zero emittance cathode. We then imposed FEL specific energy constraints and show how the Pareto Front solution shifts. Lastly, we reoptimized at various cathode emittances to map out the dependence of cathode emittance versus final emittance out of the injector system. We then determined the cathode quality needed to hit a 0.1 mm mrad 95% rms transverse emittance specification out of the current LCLS-II injector system.
	Poster WEPNEC21 [3.227 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC21
About •	paper received ※ 01 October 2019 paper accepted ※ 07 November 2019 issue date ※ 24 June 2020
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WEPNEC22	Beam Impedance Study on a Harmonic Kicker for the CCR of JLEIC	116
	G.-T. Park, J. Guo, F. Marhauser, R.A. Rimmer, H. Wang, S. Wang JLab, Newport News, Virginia, USA
	Funding: Work supported by Jefferson Science Associates, LLC under U.S DOE Contract No. DE-AC05-06OR23177 In this report, we present the development of a fast harmonic kicker, a normal conducting deflecting cavity that kicks electron bunches from ERL ring to circulator cooler ring (CCR) in Jefferson Lab Electron Ion Collider (JLEIC). This cavity utilizes 5 harmonic modes to generate a sharp kick to the electron bunch at high frequency of 86.6MHz, which is injection frequency into the CCR. The beam dynamics study and RF design of the hardware was reported in [1],[2]. In this report we present further progress including impedance by higher order mode (HOM) study and mechanical design for fabrication. [1] G. Park, et. al TUPAL068, Proc. of IPAC 2018, Apr 2018, Vancouver, BC Canada [2] G. Park, et. al, Proc. of IPAC2019, May 2019, Melbourne, Australia
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC22
About •	paper received ※ 30 September 2019 paper accepted ※ 04 November 2019 issue date ※ 24 June 2020
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WEPNEC23	Experience With LEReC High Current DC Gun
	X. Gu, Z. Altinbas, D. Bruno, L. Cannizzo, M.R. Costanzo, A.V. Fedotov, D. Kayran, C.J. Liaw, M. Mapes, K. Mernick, C. Mi, T.A. Miller, M.G. Minty, J. Sandberg, L. Smart, P. Thieberger, J.E. Tuozzolo BNL, Upton, New York, USA
	Funding: Work was supported by Brookhaven Science Associates, LLC, under Contract No. DE-SC0012704 with the U.S. Department of Energy. The Low Energy RHIC Electron Cooling (LEReC) ac-celerator was successfully commissioned at BNL. To satisfy the electron beam quality required for cooling, a high voltage DC photocathode gun was chosen as the electron source. The LEReC DC gun system is based on the Cornell University ERL gun. The gun was successfully commissioned with high-current and produced electron beam quality suitable for cooling. Here we describe operational experience with the LEReC gun, as well as experience gained with conditioning of such guns.
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WEPNEC24	Design of an Energy Recovery Linac for Coherent Electron Cooling Experiment
	Y.C. Jing, V. Litvinenko, I. Pinayev, Y.H. Wu BNL, Upton, New York, USA V. Litvinenko Stony Brook University, Stony Brook, USA K. Shih SBU, Stony Brook, New York, USA
	Funding: Work is supported by Brookhaven Science Associates, LLC under Contract No. DEAC0298-CH10886 with the U.S. Department of Energy, DOE NP office grant DEFOA-0000632, and NSF grant PHY-1415252. A Coherent electron Cooling (CeC) has a potential of substantial reducing cooling time of the high-energy hadrons and hence to boost luminosity in high-intensity hadron-hadron and electron-hadron colliders. In a CeC system, a high quality electron beam is generated, propagated and optimized through a beam line which was carefully designed with consideration of space charge effect, wakefields and nonlinear dynamics such as coherent synchrotron radiation and chromatic aberration. In this paper, we present our study on the beam dynamics of such a beam line and discuss the possibility of using an ERL for high repetition operation.
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WEPNEC25	Research on Alkali Antimonide Photocathode Fabrication Recipe at PKU	120
	D.M. Ouyang, L.W. Feng, S. Huang, K.X. Liu, S.W. Quan, H.M. Xie, X.K. Zhang, S. Zhao PKU, Beijing, People’s Republic of China
	Low emittance, high QE and long lifetime photocathode is widely studied for X-ray Free Electron Laser (XFEL)and Energy Recovery Linacs (ERL) applications. A deposition system for alkali antimonide photocathode (K2CsSb, Cs3Sb etc.) is being commissioned at Peking University. In this paper, we present our experimental results on alkali antimonide photocathode with this deposition system. We successfully fabricated Cs3Sb photocathode on oxygen free copper, p-type Si (100) and Mo substrates with QE of 1.4%, 2.6% and 2.6% respectively.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC25
About •	paper received ※ 27 September 2019 paper accepted ※ 01 November 2019 issue date ※ 24 June 2020
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Paper

Title

Page

Status and Future Perspective of the TRIUMF E-Linac

70

S.D. Rädel, M. Alcorta, F. Ames, E. Chapman, K. Fong, B. Humphries, O.K. Kester, D. Kishi, S.R. Koscielniak, R.E. Laxdal, Y. Ma, T. Planche, M. Rowe, V.A. Verzilov
TRIUMF, Vancouver, Canada

The currently installed configuration of TRIUMF’s superconducting electron linac (e-linac) can produce an electron beam up to 30MeV and 10mA. Low beam power commissioning of the segment spanning the electron gun to high energy dump took place in summer 2018 with an attained beam energy of 25MeV. As the driver of the ARIEL project, the e-linac will deliver electrons to a photo-converter target station for the production of neutron-rich rare isotope beams (RIB) via photo fission. The e-linac will have sufficient beam power to support the demands of other user community rare isotope beams. This driver accelerator could server as a production machine for high field THz radiation and as irradiation center. A recirculation of the beam would be beneficial for RIB production at higher beam energy and would allow for high bunch compression to generate THz radiation. Such a system would also allow for the investigation of a high beam intensity energy recovery linac. To this end, TRIUMF is investigating the design of such a recirculation and the beam dynamics as a first step.

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reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC01

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paper received ※ 01 October 2019 paper accepted ※ 01 November 2019 issue date ※ 24 June 2020

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WEPNEC02

Investigation and Mitigation of the Mie-Scattering on the Surface of the First Objective Lens for Coronagraph-Based Halo Monitor

J.G. Hwang, J. Kuszynski
HZB, Berlin, Germany

Funding: This work was supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association.
Since, due to the heat capacity of the cryogenics, additional heat load on a cryogenic system as a result of uncontrolled beam losses is only allowed to be below 50 W which corresponds to 10^-5 respected to the full power of BERLinPro, the development of diagnostics which can measure the intensity in the order of 10^-5 is crucial. In our previous beam test of the coronagraph-based halo monitor with various operation modes of the BESSY II storage ring, the limitation of the measurement of the halo distribution was to be 10^-4 respected to the core intensity due to the noise produced by scattered light from digs and scratches of the first objective lens. In order to mitigate the noise level produced from the surface of the objective lens to reach 10^-5 to 10^-6, the Mie-scattering effect was investigated, and furthermore, a high-quality surface lens was purchased.

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WEPNEC03

Thermal Load Studies on the Photocathode Insert with Exchangeable Plug for the BERLinPro SRF-Photoinjector

N. Al-Saokal, M. Bürger, M. Dirsat, A. Frahm, A. Jankowiak, T. Kamps, G. Klemz, J. Kühn, S. Mistry, A. Neumann, H. Plötz
HZB, Berlin, Germany

For the operation of an SRF photoinjector a well-functioning and efficient cooling system of the photocathode is necessary. A test experiment was set up of the photocathode cooling system based on the original components, which we call thermal contact experiment (TCX). We present the results of our thermal load studies on the photocathode insert with exchangeable photocathode plug. The goal was to test all components before they are installed in the cold string of the BERLinPro SRF-Photoinjector to ensure the operation of very sensitive semiconductor photocathodes. The tests include the investigation of the cooling performance, the thermal load management and the mechanical stability of the photocathode insert.

Poster WEPNEC03 [1.703 MB]

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WEPNEC04

HOM Damping for High Current SRF Cavity

W. Xu
BNL, Upton, New York, USA

Funding: * Work supported by LDRD program of Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
High power HOM damper is a challenge for high current SRF accelerator. In the past few years, we developed two types of high power HOM damper: a novel rigid waveguide high power HOM damping scheme and a room temperature SiC beampipe absorbing scheme. This presentation will present the design and test results of these two HOM damping schemes.

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WEPNEC06

Radiation Protection Instrumentation of BERLinPro

L. Pichl, Y. Bergmann, A. Bundels, K. Ottpresenter
HZB, Berlin, Germany

Funding: Work supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association
The Energy Recovery Linac project BERLinPro is a test facility to study the beam parameter range necessary for an ERL as synchrotron light source [1]. It is currently under construction and is designed to operate with the maximum beam parameters of 50 MeV and 100 mA cw current. Even if the electron losses within the recirculator are limited to 0.6 % due to the available rf power, (at higher losses an immediate beam break-up occurs because of the ERL principle) the beam loss power can be by orders of magnitude higher than in electron storage rings used for synchrotron radiation. The Fluka [2,3] calculations of the resulting activations of machine components and air activations have been discussed in earlier papers [4,5]. In this work we present the components of the ambient dosimetry, the measurement system of air activations and their inclusion in the personal safety system. Additionally we present recent calculations of the activation of cooling water and the method of storing and measuring it in case of a leakage.
1 M Abo-Bakr et al SRF2009 Berlin
2 G Battistoni et al AIP Conf. Proc. 896 2007
3 A Fasso et al CERN-2005-10 2005
4 M Helmecke et al RADSYNCH2013 BNL
5 K Ott et al RADSYNCH2015 DESY

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WEPNEC07

Comparison of Two Pareto Optimization Tools Using OPAL and ASTRA for a Dedicated BERLinPro Injector Optimization.

J. Völker
HZB, Berlin, Germany
A. Adelmann
PSI, Villigen PSI, Switzerland

BERLinPro is an Energy Recovery Linac (ERL) Project, currently being set up at the HZB. The accelerator consists of an injector part (SRF photo injector and booster section) and the ERL part (LINAC and recirculator section). Until realization of the final ERL setup further beam applications are under development using only the injector part of BERLinPro, like ultrafast electron diffraction (UED) or tomography experiments. For those cases a dedicated beam optic for the complete injector is required that differ from the standard ERL optics. Especially for UED experiments, an extreme short electron bunch and a tiny transverse emittance are needed. For the optimization of the injector two multi-parameter Pareto optimization tools were used. On the one hand, ASTRA with an external MATLAB optimizer, on the other hand, OPAL** with its new internal optimization tool. In this paper we will present both generic methods and compare their results.

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WEPNEC08

Dispersion Matching With Space Charge in MESA

74

A. Khan, O. Boine-Frankenheim
TEMF, TU Darmstadt, Darmstadt, Germany
K. Aulenbacher
IKP, Mainz, Germany

Funding: Supported by the DFG through GRK 2128.
For intense electron bunches traversing through bends, as for example the recirculation arcs of an Energy-Recovery Linac (ERL), dispersion matching with space charge of an arc into the subsequent radio-frequency (RF) structure is essential to maintain the beam quality. We show that beam envelopes and dispersion along the bends and recirculation arcs of an ERL, including space charge forces, can be matched to adjust the beam to the parameters of the subsequent section. The present study is focused on a small-scale, double-sided recirculating linac Mainz Energy-recovering Superconducting Accelerator (MESA). MESA is an under construction two pass ERL at the Johannes Gutenberg-Universit\"at Mainz, which should deliver a continuous wave (CW) beam at 10⁵ MeV for physics experiments with a pseudo-internal target. In this work, a coupled transverse-longitudinal beam matrix approach for matching with space charge in MESA is employed.

Poster WEPNEC08 [1.190 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC08

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paper received ※ 12 September 2019 paper accepted ※ 01 November 2019 issue date ※ 24 June 2020

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WEPNEC09

Thz User Operation With 200 pC CW Beam Generated by the ELBE SRF Gun II

A. Arnold, S. Ma, P. Murcek, J. Schaber, J. Teichert, R. Xiang, P.Z. Zwartek
HZDR, Dresden, Germany

Funding: The work was partly supported by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1 and Deutsche Forschungsgemeinschaft (DFG) project (XI 10⁶/2-1)
As a new electron source with higher brilliance, the second superconducting RF photoinjector (SRF Gun II) has been built at the ELBE radiation center for high power radiation sources. One of the main goals of SRF gun II is to achieve a higher bunch charge (>200 pC) and lower emittance (3 mm mrad) than the present ELBE thermionic DC gun. SRF Gun II features a 3.5-cell niobium cavity as well as a superconducting solenoid in the same cryomodule. With Mg photocathodes the gun is able to provide medium current beam with bunch charge of more than 200 pC and sub-ps bunch length at 100 kHz repetition rate. With this contribution we present convincing results from long-term user operation of SRF gun II in combination with the bunching concept of the ELBE accelerator in order to produce THz radiation with much higher stability and power than available using the existing thermionic gun.

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WEPNEC10

Investigation on the Ion Clearing of Multi-Purpose Electrodes of BERLinPro

80

G. Pöplau
COMPAEC e.G., Rostock, Germany
A. Meseck
KPH, Mainz, Germany
A. Meseck
HZB, Berlin, Germany

High-brightness electron beams provided by modern accelerators require several measures to preserve their high quality and to avoid instabilities. The mitigation of the impact of residual ions is one of these measures. It is particularly important if high bunch charges in combination with high repetition rates are aimed for. This is because ions can be trapped in the strong negative electrical potential of the electron beam causing emittance blow-up, increased beam halo and longitudinal and transverse instabilities. One ion-clearing strategy is the installation of clearing electrodes. Of particular interest in this context is the performance of multi-purpose electrodes, which are designed such that they allow for a simultaneous ion-clearing and beam-position monitoring. Such electrodes will be installed in the BERLinPro facility. In this contribution, we present numerical studies of the performance of multi-purpose clearing-electrodes planned for BERLinPro, i.e. we investigate the behavior of ions generated by electron bunches while passing through the field of the electrodes. Hereby, several ion species and configurations of electrodes are considered.

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reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC10

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paper received ※ 11 October 2019 paper accepted ※ 06 November 2019 issue date ※ 24 June 2020

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WEPNEC11

X-Ray ICS Source Based on Modified Push-Pull ERLs

84

I. Drebot, A. Bacci, S. Cialdi, L. Faillace, D. Giannotti, M. Rossetti Conti, A.R. Rossi, L. Serafini, M. Statera, V. Torri
INFN-Milano, Milano, Italy
A. Bosotti, F. Broggi, D. Giove, P. Michelato, L. Monaco, R. Paparella, D. Sertore
INFN/LASA, Segrate (MI), Italy
P. Cardarelli, M. Gambaccini, G. Paternò, A. Taibi
INFN-Ferrara, Ferrara, Italy
A. Esposito, A. Gallo, C. Vaccarezza
INFN/LNF, Frascati, Italy
G. Galzerano
POLIMI, Milano, Italy
M. Gambaccini
UNIFE, Ferrara, Italy
G. Mettivier, P. Russo
UniNa, Napoli, Italy
V. Petrillo, F. Prelz
Universita’ degli Studi di Milano & INFN, Milano, Italy
E. Puppin
Politecnico/Milano, Milano, Italy
A. Sarno
INFN-Napoli, Napoli, Italy

We present the conceptual designs of BriXS and BriXSino (a minimal test-bench demonstrator of proof of principle) for a compact X-ray Source based on innovative push-pull ERLs. BriXS, the first stage of the Marix project, is a Compton X-ray source based on superconducting cavity technology with energy recirculation and on a laser system in Fabry-Pérot cavity at a repetition rate of 100 MHz, producing 20-180 keV radiation for medical applications. The energy recovery scheme based on a modified folded push-pull CW-SC twin Linac ensemble allows to sustain MW-class beam power with almost just one hundred kW active power dissipation/consumption.

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reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC11

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paper received ※ 20 September 2019 paper accepted ※ 06 November 2019 issue date ※ 24 June 2020

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WEPNEC12

Beam Optics of Bunch Compression at Compact ERL

M. Shimada, Y. Honda, R. Kato, T. Miyajima, N. Nakamura, T. Obina
KEK, Ibaraki, Japan

Short electron bunch is essential for THz coherent transition radiation or FEL oscillation. Therefore, the bunch compression is studied at the compact ERL in KEK site. We demonstrated it and experimentally evaluated the bunch length and the transverse emittance. The results of the optics and beam commissioning will be presented.

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WEPNEC13

Preliminary Investigations and Pre-Research Scheme of High Average Current Electron Injectors at IMP

90

Q.T. Zhao, J.C. Yang, Z.M. Zhang, H.W. Zhao
IMP/CAS, Lanzhou, People’s Republic of China

High average current electron injectors are desired by high average beam power SRF linacs. With respect to the different linac application, different beam qualities are required. Two kinds of electron gun are planned for future projects at IMP, one is thermionic electron gun dedicated for high average current, and another one is photocathode gun which is for high average current and high beam quality or even with high polarization. Current status and development of the high average current electron source are investigated and summarized. The thermionic gun studies are planned and the feasible types of gun for the future Electron ion collider of China (EicC) project are also proposed. The pre-research scheme of these two kinds of electron guns are schemed, which will be the start of high average current and high-quality electron source development at Institute of modern physics (IMP), Chinese academy of sciences (CAS).

Poster WEPNEC13 [0.827 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC13

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paper received ※ 22 September 2019 paper accepted ※ 01 November 2019 issue date ※ 24 June 2020

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WEPNEC14

Electromagnetic Design of a Superconducting dual axis Spoke Cavity*

94

Ya.V. Shashkov, N.Yu. Samarokov
MEPhI, Moscow, Russia
I.V. Konoplev
JAI, Oxford, United Kingdom

Funding: The reported study was funded by RFBR according to the research project 18-302-00990
Dual axis superconducting spoke cavity for Energy Recovery Linac application is proposed. Conceptual design of the cavity is shown and preliminary optimiza-tions of the proposed structure have been carried out to minimize the ratio of the peak magnetic and electric fields to the accelerating voltage. The new design and future work are discussed

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reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC14

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paper received ※ 01 October 2019 paper accepted ※ 06 November 2019 issue date ※ 24 June 2020

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WEPNEC16

Electron Outcoupling System of Novosibirsk Free Electron Laser Facility - Beam Dynamics Calculation and the First Experiments

98

Ya.V. Getmanov, A.S. Matveev, O.A. Shevchenko, N.A. Vinokurov
BINP SB RAS, Novosibirsk, Russia
Ya.V. Getmanov, A.S. Matveev, N.A. Vinokurov
NSU, Novosibirsk, Russia

The radiation power of the FEL with optical cavity can be limited by the overheating of reflecting mirrors. In the electron outcoupling scheme electron beam radiates the main power at a slight angle to the optical axis. For this, it is necessary to divide undulator by a dipole magnet at least in two parts - the first for the electron beam bunching in the field of the main optical mode, and the second for the power radiation by deflected beam. Electron outcoupling system is installed on the third FEL based on the multiturn energy recovery linac of the Novosibirsk Free Electron Laser facility (NovoFEL). It consists of three undulators, dipole correctors and two quadrupole lenses assembled between them. There are two different configurations of the system since the electrons can be deflected in either the second or the third undulator. The electron beam dynamics calculations and the results of the first experiments are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC16

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paper received ※ 01 October 2019 paper accepted ※ 06 November 2019 issue date ※ 24 June 2020

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WEPNEC17

Developments in Photocathode R&D at STFC Daresbury Laboratory: New Transverse Energy Spread Measurements and the Development of a Multi-Alkali Photocathode Preparation Facility

103

L.B. Jones, B.L. Militsyn, T.C.Q. Noakes
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
L.B. Jones, D.P. Juarez-Lopez, B.L. Militsyn, T.C.Q. Noakes, L.A.J. Soomary, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
D.P. Juarez-Lopez, L.A.J. Soomary, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

Photocathode R&D activity within ASTeC is focussed on further development of the tools required for the preparation and characterisation of high performance photocathodes for X-FELs. Our Transverse Energy Spread Spectrometer (TESS)* experimental facility can be used with III-V semiconductor, multi-alkali and metal photocathodes to measure transverse and longitudinal energy distributions of the emitted electrons. Recently TESS has been upgraded to increase the instrument sensitivity for operation with low QE materials under UV illumination. Our R&D facilities also include in-vacuum quantum efficiency measurement, XPS, STM, plus ex-vacuum optical and STM microscopy for surface metrology. Intrinsic photocathode emittance is affected by many factors including illumination wavelength and surface roughness. We present energy distribution measurements for electrons emitted from copper, niobium and zirconium photocathode samples with measured levels of surface roughness under illumination by wavelengths between 256 and 291 nm. We also present an update on progress to establish a multi-alkali photocathode preparation facility to support the CLARA** linear accelerator.
* Proc. FEL’13, TUPPS033, 290-293
** CLARA Conceptual Design Report J. Inst. 9 T05001

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reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC17

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paper received ※ 04 October 2019 paper accepted ※ 01 November 2019 issue date ※ 24 June 2020

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WEPNEC18

Analytic Longitudinal Phase Space Solutions for Multipass Energy Recovery Linacs

P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
I.R. Bailey, P.H. Williams
Cockcroft Institute, Warrington, Cheshire, United Kingdom
I.R. Bailey
Lancaster University, Lancaster, United Kingdom
T.K. Charles
The University of Melbourne, Melbourne, Victoria, Australia
T.K. Charles
CERN, Geneva, Switzerland
G. Perez-Seguranapresenter
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

The longitudinal solution space of an energy recovery linac is an under-constrained system. For applications where we wish to compress the bunches for delivery to, for example, a free-electron laser or an interaction point, and simultaneously ensure full recovery it is useful to be able to rapidly ascertain and assess the possible solutions. Moreover, when we consider multi-pass ERLS, we quickly conclude that a trial-and-error approach to deriving such solutions (through for example one-dimensional particle tracking) is impractical. Here we extend an analytic recurrence method of deriving phase space solutions in multistage compression schemes, due to Zagorodnov & Dohlus, to multi-pass energy recovery linac systems. We use this method to categorise classes of solutions, and explore the implications of the energy recovery condition.

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WEPNEC19

Optimisation of the PERLE Injector

107

B. Hounsell, M. Klein, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
B. Hounsell, B.L. Militsyn, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
B. Hounsell, W. Kaabi
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The injector for PERLE, a proposed electron Energy Recovery Linac (ERL) test facility for the LHeC and FCC-eh projects, is intended to deliver 500 pC bunches at a repetition rate of 40.1 MHz for a total beam current of 20 mA. These bunches must have a bunch length of 3 mm rms and an energy of 7 MeV at the entrance to the first linac pass while simultaneously achieving a transverse emittance of less than 6 mm mrad. The injector is based around a DC photocathode electron gun, followed by a focusing and normal conducting bunching section, a booster with 5 independently controllable SRF cavities and a merger into the main ERL. A design for this injector from the photocathode to the exit of the booster is presented. This design was simulated using ASTRA for the beam dynamics simulations and optimized using the many objective optimization algorithm NSGAIII. The use of NSGAIII allows more than three beam parameters to be optimised simultaneously and the trade-offs between them to be explored.

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reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC19

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paper received ※ 01 October 2019 paper accepted ※ 11 November 2019 issue date ※ 24 June 2020

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WEPNEC20

A Hard X-ray Compact Compton Source at CBETA

J. Crone, H.L. Owen
UMAN, Manchester, United Kingdom
K.E. Deitrick, C. Franck, K.W. Smolenski
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
B.D. Muratori
Cockcroft Institute, Warrington, Cheshire, United Kingdom
B.D. Muratori
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Compton backscattering at energy recovery linacs (ERLs) promise high flux, high energy x-ray sources in the future, made possible by high quality, high repetition rate electron beams produced by ERLs. CBETA, the Cornell-Brookhaven accelerator currently being commissioned at Cornell, is an SRF multi-turn ERL using Non-Scaling Fixed Field Alternating Gradient (NS-FFA) arcs. CBETA has high quality design parameters with an anticipated top energy of 150 MeV on the fourth pass. The expected parameters of a Compton source at CBETA include a top x-ray energy of over 400 keV with a flux on the order of 10¹² ph/s. One particular application requiring a high energy, high flux source is spectroscopy in high energy atomic physics. In this paper, we present anticipated parameters and potential applications in science and engineering for this source.

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WEPNEC21

Decoupling Cathode and Lattice Emittance Contributions from a 100 pC, 100 MeV Electron Injector System

112

N.P. Norvell
SLAC, Menlo Park, California, USA
M.B. Andorf, I.V. Bazarov, C.M. Gulliford, J.M. Maxson
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

We present simulation results to decouple the emittance contributions that are intrinsic from the injector lattice versus emittance contributions due to the quality of the cathode out of a 100 MeV electron injector system. Using ASTRA driven by the NSGA-II genetic algorithm, we optimized the LCLS-II injector system with a zero emittance cathode. We then imposed FEL specific energy constraints and show how the Pareto Front solution shifts. Lastly, we reoptimized at various cathode emittances to map out the dependence of cathode emittance versus final emittance out of the injector system. We then determined the cathode quality needed to hit a 0.1 mm mrad 95% rms transverse emittance specification out of the current LCLS-II injector system.

Poster WEPNEC21 [3.227 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC21

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paper received ※ 01 October 2019 paper accepted ※ 07 November 2019 issue date ※ 24 June 2020

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WEPNEC22

Beam Impedance Study on a Harmonic Kicker for the CCR of JLEIC

116

G.-T. Park, J. Guo, F. Marhauser, R.A. Rimmer, H. Wang, S. Wang
JLab, Newport News, Virginia, USA

Funding: Work supported by Jefferson Science Associates, LLC under U.S DOE Contract No. DE-AC05-06OR23177
In this report, we present the development of a fast harmonic kicker, a normal conducting deflecting cavity that kicks electron bunches from ERL ring to circulator cooler ring (CCR) in Jefferson Lab Electron Ion Collider (JLEIC). This cavity utilizes 5 harmonic modes to generate a sharp kick to the electron bunch at high frequency of 86.6MHz, which is injection frequency into the CCR. The beam dynamics study and RF design of the hardware was reported in [1],[2]. In this report we present further progress including impedance by higher order mode (HOM) study and mechanical design for fabrication.
[1] G. Park, et. al TUPAL068, Proc. of IPAC 2018, Apr 2018, Vancouver, BC Canada
[2] G. Park, et. al, Proc. of IPAC2019, May 2019, Melbourne, Australia

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reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC22

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paper received ※ 30 September 2019 paper accepted ※ 04 November 2019 issue date ※ 24 June 2020

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WEPNEC23

Experience With LEReC High Current DC Gun

X. Gu, Z. Altinbas, D. Bruno, L. Cannizzo, M.R. Costanzo, A.V. Fedotov, D. Kayran, C.J. Liaw, M. Mapes, K. Mernick, C. Mi, T.A. Miller, M.G. Minty, J. Sandberg, L. Smart, P. Thieberger, J.E. Tuozzolo
BNL, Upton, New York, USA

Funding: Work was supported by Brookhaven Science Associates, LLC, under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The Low Energy RHIC Electron Cooling (LEReC) ac-celerator was successfully commissioned at BNL. To satisfy the electron beam quality required for cooling, a high voltage DC photocathode gun was chosen as the electron source. The LEReC DC gun system is based on the Cornell University ERL gun. The gun was successfully commissioned with high-current and produced electron beam quality suitable for cooling. Here we describe operational experience with the LEReC gun, as well as experience gained with conditioning of such guns.

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WEPNEC24

Design of an Energy Recovery Linac for Coherent Electron Cooling Experiment

Y.C. Jing, V. Litvinenko, I. Pinayev, Y.H. Wu
BNL, Upton, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA
K. Shih
SBU, Stony Brook, New York, USA

Funding: Work is supported by Brookhaven Science Associates, LLC under Contract No. DEAC0298-CH10886 with the U.S. Department of Energy, DOE NP office grant DEFOA-0000632, and NSF grant PHY-1415252.
A Coherent electron Cooling (CeC) has a potential of substantial reducing cooling time of the high-energy hadrons and hence to boost luminosity in high-intensity hadron-hadron and electron-hadron colliders. In a CeC system, a high quality electron beam is generated, propagated and optimized through a beam line which was carefully designed with consideration of space charge effect, wakefields and nonlinear dynamics such as coherent synchrotron radiation and chromatic aberration. In this paper, we present our study on the beam dynamics of such a beam line and discuss the possibility of using an ERL for high repetition operation.

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WEPNEC25

Research on Alkali Antimonide Photocathode Fabrication Recipe at PKU

120

D.M. Ouyang, L.W. Feng, S. Huang, K.X. Liu, S.W. Quan, H.M. Xie, X.K. Zhang, S. Zhao
PKU, Beijing, People’s Republic of China

Low emittance, high QE and long lifetime photocathode is widely studied for X-ray Free Electron Laser (XFEL)and Energy Recovery Linacs (ERL) applications. A deposition system for alkali antimonide photocathode (K2CsSb, Cs3Sb etc.) is being commissioned at Peking University. In this paper, we present our experimental results on alkali antimonide photocathode with this deposition system. We successfully fabricated Cs3Sb photocathode on oxygen free copper, p-type Si (100) and Mo substrates with QE of 1.4%, 2.6% and 2.6% respectively.

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reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC25

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paper received ※ 27 September 2019 paper accepted ※ 01 November 2019 issue date ※ 24 June 2020

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